Mountains rise up form the ground and the highest mountain peak in our world is Mount Everest, which is 8850 meters higher than the sea level. However, the conditions on the top of Mt. Everest is not the same as that at our home. Its extreme and is difficult for human beings to survive for a long time there. Apart from the visible differences in the terrain and geographic features, the major 'invisible difference' is the effects of the high altitude on human body. That is what makes it the 'first challenge of a mountaineer'. Be it for achieving the summit or just for the love of it, human beings have been challenging it are successfully achieving it.

Perhaps its the nature of us humans to accept challenges and to see the World beyond the challenges... The love of the mountains is such a sport that makes us venture outdoors, as the mountains wont be coming to us anyways ;-) In dong so, a mountaineer has to overcome lots of challenges of harsh and extreme weather, rough and volatile terrain, living and sustaining out of one's comfort zone, physical demands and the most important of them all - The Chemistry Of High Altitude.

Mountaineering involves scaling altitudes and due to the change in atmospheric pressure with altitude ( inversely proportional ), our body's default environment changes. We need to adapt to those changes in environment physically and mentally, within our time frame, to achieve our objectives in the mountains. This has raised the importance of studying the high altitude and its effects on the human body, so that we can find a formula to break the challenge. This study classifies the High Altitude according to its magnitude. The most common classification is -

As we know that with increase in altitude, the atmospheric pressure decreases. The concentration of oxygen at sea level is 21% approximately and the mercuric pressure is approximately 760 mmHg. Our body is very well adapted to these conditions. However, with increase in altitude, the atmospheric pressure decreases which gives more space for the air molecules to spread wide apart from each other. So, even if the concentration of oxygen in the atmosphere remains constant, our oxygen molecule intake per breath decreases. Just to imagine, if we had been breathing 100 oxygen molecules per breath, at 3000 meters we would be breathing in about 80 oxygen molecules per breath.

That's unusual for our body which detects the change and responds to the change by increasing in our breathing rate ( hypoxia) to meet the oxygen deficiency. We call it 'breathlessness' in laymen terms. We try to breathe more to consume more air. On the other hand, the body increases the Hemoglobin count in our blood which are the oxygen carriers, to hold more oxygen molecules in our blood. This process thickens our blood and hence our heart now needs to pump thicker blood to the extreme organs, which further results in increased pressure on our heart. So a slight increase in blood pressure and pulse rate in the high altitude is our body's reaction to respond to the change environment, and is usually considered normal as you cannot do much about it.

In order to breathe more oxygen from the air by increasing the breathe rate, we also loose Carbon Dioxide at a faster rate due to exhalation. The concentration of CO2 goes below normal due to it. Excessive hypoxia makes our blood alkaline and our kidneys react immediately by eliminating bicarbonates with the urine to restore the blood pH level. That's why we urinate more in High Altitude.

At around 5000 meters, the pressure is approximately half compared to that at sea level and at the summit of Mt. Everest, its one-third. Our body is not just used to this deficiency of oxygen in our blood, hence we face several problems which clubbed together is called Acute Mountain Sickness ( AMS) or simply Altitude Sickness.

As described above, AMS is caused by our body's inability or slowness to adapt to the high altitude. Our body's chemistry, unable to cope up to the harsh conditions, start to deteriorate and fail. It initially rings the bell by showing various symptoms ( single or combined ) like headache, dizziness, fatigue, breathlessness, nausea, feeling vomitish, etc. These symptoms clubbed together is called Acute Mountain Sickness.

Treatment: resolves on its own after spending some time in that altitude. Mild analgesic or ibubrufen may be given for headache. Hydrate the victim and recheck after some time. Do not exert physically and rest in camp. Keep a strict watch on the victim. Restrict further ascent until the symptoms vanish, else descend if symptoms persist. You may put the patient on Acetazolomide ( Diamox - 125mg twice a day post food, if required 250 mg twice a day) for the night and if symptoms still persist, descend is the only solution. Do not force food. Let hunger come naturally. Its very unusual for our body to not feel hungry at that altitude where our metabolism increases and we exhaust easily. The most important decision to keep in mind is NOT TO CLIMB UP WITH THE SYMPTOMS

Usually, AMS heals on its own when ample amount of time is spent at that altitude. However, further ascend should not be allowed if the symptoms do not resolve. AMS should always be seen as a dangerous alarm for two of the deadliest and fatal conditions at High Altitude - High Altitude Pulmonary Edema (HAPE) and High Altitude Cerebral Edema (HACE).

If AMS alarm is not heard, you might be taking yourself to your death bed high up in the mountains.

HAPE is a condition in which the pressure in our pulmonary artery increase so much that it ruptures the week capillaries, specially that of our lungs which is badly Hypoxic. This results in leakage of fluids in our lungs and we have difficulty breathing. HAPE generally happens on the second night, but you should always be on check. Cold conditions increase artery pressure, and increase chances of HAPE.

Treatments: You cannot treat HAPE at high altitude. You can only reduce the symptoms by giving drugs like Nifidipine ( 8mg). Provide supplementary Oxygen. Victim should be kept warm. Sometime, you might put the victim on Acetazolomide (Diamox) + Nifidipine. Stop any exertion, even while descending. The ultimate course of action is immediate evacuation as soon as possible, even during night if required. The symptoms resolves on descend, but the victim must be taken to hospital for proper management.

Caution should be made not to confuse HAPE with bronchitis, pneumonia or asthma. A HAPE patient will improve on descending.

HACE is a condition in which brain functions improperly due to the effects of altitude. The pressure in the cerebral membrane increase and the brain swells. It can be very dangerous and sometimes might not give you time to react.

Treatments: Similarly to that of HAPE, high altitude is not the place to treat HACE. Only solution is to descend, and HACE patients show quick signs of recovery on descending good altitude. Medicines like Dexamethasone ( 8mg) can be given, sometimes along with Acetazolomide ( Diamox) to give you time to work out evacuation, if required even at night.

To our relief, our body is a miracle machine. Acclimatization is the process by which our body adapts to the extreme conditions of High Altitude Hypoxia.

Acclimatization is the process in which an individual body copes up and adjusts to the change in its environment. The various factors of the environment change may be cold, heat, altitude from sea level, atmospheric pressure, etc. It allows the body to remain normal and maintain performance across a range of environmental conditions.

Acclimatization is the only better answer to High Altitude Conditions. We need to acclimatize well to complete a high altitude trek. Our body is designed to acclimatize naturally.

How Do Human Body Acclimatize To High Altitude ? With increase in altitude, the atmospheric pressure decreases which gives more space to the air molecules and the oxygen molecules goes far apart from each other. This results is low oxygen molecule per breath. Our body detects that and responds by increasing in breathe rate ( hypoxia) We call it breathlessness in laymen terms. We try to breathe more to consume more air. On the other hand, the body increases the Hemoglobin count in our blood which are the oxygen carriers to hold more oxygen molecules in our blood. This process thickens our blood and hence our heart now need to pump thicker blood to the extreme organs, which further results in increased blood pressure. So a slight increased blood pressure and pulse rate in the high altitude is normal.

Acclimatization is a process which takes time depending on the individual body. Few acclimatize faster, whereas few take little more time. There are two kinds of acclimatization - Shorter and Longer. Longer acclimatization might take long time. The approximate formula is the altitude in kilometers multiplied by 11.6 days. So to acclimatize for a normal trek that goes up to 4000 meters, it might take 4 X 11.6 = 46 days!!

Diamox is acetazolomide which aids faster acclimatization. Diamox is a diuretic and helps the kidneys excrete the bicarbonates. As a result of Hypoxia, our body breathes rapidly, which decreases the saturation and partial pressure of CO2 in our body. This increases the pH of our blood and makes it alkaline. It is here where Diamox come into picture and does its work. It is a diuretic and helps remove excess water and salt from the body, making the blood thinner and hence lowering the blood pressure as well.

Periodic breathing is a irregular pattern of breathing that occurs at high altitude, specially during night. The breath might stop for few seconds and it might create tremendous anxiety preventing you to sleep further. Do not worry, its normal, and betters with proper acclimatization. Diamox helps with periodic breathing, 125 mg before sleep.

Sleeping is very important to you as a better sleep means faster acclimatization and better recovery for the next day

Sleeping pills should not be taken at high altitude. It might throw you into problems at high altitude to AMS. Melatonin is an OTC sleep aid that helps many and has no contraindications at altitude. One prescription sleep aid that has shown NOT to disturb breathing at sleep is zoldipem; you may want to discuss taking this medication with your personal physician. Any other hypnotics/tranquilizers should probably not be used at altitude.?

A Loyal Himalayan Lover, Trekker, Mountaineer, Photographer and Researcher. A Computer Science Engineer by education and Ex. Software Developer for the IT companies. He has learnt from mistakes and not from books - His Own, his friends, whom he met and lots of other trekker friends whom he lead for treks deep and high in the Himalayas. Having born and grown up in the lap of the Himalayas, playing with different elements of the Himalayas, its undoubtedly his best friend. Having said that, he is very biased, protective and caring of the Himalayas. Few of his friends say he is strict, in following rules and safety practices on a Himalayan trek. That's very true. It has come from the practical teachings by the Mighty Himalayas and he takes no chances, specially when he is leading a group.

He is the founder of Himalayan High and with it, his intentions are much bigger, wider and future thought, as a step to preach responsible trekking and make trekking sustainable, pass on this beautiful sport to the next generations. Learn more about Himalayan High on About Himalayan High